1. Field of the Invention
This invention relates generally to semiconductor processing, and more particularly to semiconductor workpieces or wafers and to methods of dicing the same.
2. Description of the Related Art
Conventional semiconductor chips are routinely fabricated en masse in large groups as part of a single semiconductor wafer. At the conclusion of the processing steps to form the individual dice, a so-called dicing or sawing operation is performed on the wafer to cut out the individual dice. Thereafter, the dice may be packaged or directly mounted to a printed circuit board of one form or another. Conventional semiconductor dice are routinely cut out from the wafer as rectangular shapes. Many conventional semiconductor dice have four sides and four corners. The dicing operation is a mechanical cutting operation performed with a type of circular saw. Dicing saws are made with great care and operate more precisely than a comparable masonry circular saw.
Despite the aforementioned refinements, conventional dicing saw blades can still cause difficulties for certain types of semiconductor wafers and the chips cut from them. The problem stems from the structure of the wafer and chips. Many types of semiconductor chips dissipate sufficient levels of power that appropriate thermal management calls for the usage of solder-type thermal interface materials to convey heat to a heat spreader. Silicon typically does not exhibit favorable solder wettable properties. Accordingly, such semiconductor chips, and the wafers that spawn them, frequently include backside structure that may be a unitary or laminate structure of materials that provide a solder wettable interface between the semiconductor chip and the solder type thermal interface material. A difficulty associated with dicing of a semiconductor wafer that includes a backside metallization structure is the potential for the saw blade to kick flecks of the backside metallization structure up out of the semiconductor chip at the tail end of the dicing process for a given dicing street. These flecks may land harmlessly off of the semiconductor wafer. However, such flecks may also land on the front side of a semiconductor wafer and even onto solder bumps or onto two or more solder bumps at once, which can create a short between two or more bumps. Such shorts may persist even after a solder reflow process to mount the semiconductor chips to a circuit board of one sort or another.
The present invention is directed to overcoming or reducing the effects of one or more of the foregoing disadvantages.